Is it possible to have a node value correspond to how much light is hitting that pixel?
I think you need to bake diffuse indirect/direct to a texture and then use that as a source for incoming light. IFAIK it would be hard to know in forehand how much light ended up hitting a particular point on a surface before everything is calculated.

Another way would to do this in compositing where you could render the globe with a white material and use the inverted image as a mask where to let the light show.